The present disclosure relates generally to a clearance control system for use in aerospace applications and, more specifically, to a manifold for use in the clearance control system.
At least some known gas turbine engines, such as aircraft engines, include an engine casing that extends circumferentially about a compressor and a turbine that each include a rotor assembly and a stator assembly. Known rotor assemblies include at least one row of rotating blades that extend radially outward from a blade root coupled to the rotor assembly, to a blade tip that passes proximate the stator assembly. A radial tip clearance is defined between the rotating blade tips and a stationary shroud attached to the engine casing.
In these known assemblies, during engine operation, variations in the thermal environment in the engine may cause thermal expansion or contraction of the rotor and stator assemblies. Such thermal expansion or contraction may not occur uniformly in magnitude or rate. As a result, inadvertent rubbing, such as between the rotor blade tips and the shroud may occur. Moreover, radial clearances may be created that are wider than acceptable the design clearances. These wider clearances may adversely affect engine performance. Continued rubbing between the rotor blade tips and engine casing may lead to premature failure of the rotor blade.
At least some known aircraft engines use active clearance control systems to control the thermal expansion or contraction of the engine casing. For example, at least some known active clearance control systems discharge a flow of air from the compressor, or other suitable fluid sources, towards the engine casing. In some embodiments, the flow of air is discharged from a manifold extending circumferentially about the engine casing. The manifold is typically manufactured from sheet metal, and is formed in a roll forming process. However, the thickness of the sheet metal and the process used to form the manifold generally limits the final shape of the manifold. Moreover, the thickness of the sheet metal is typically limited to reduce the weight of the aircraft engine.